设计模式(1)单例模式

程序中有时候需要保存全局的数据,比如程序的配置文件,需要随时检索的.比如程序中有些变量需要全局保存全局用,这时候我们不想用一个全局变量来保存

这时候,可以使用单例模式,从名称可以看出,单例模式就是类的实例全局只创建一个.怎么样才能保存只创建一个实例呢?

我们可以设置标识位,创建过的就不再创建了.下面是单例的简单实现

  template<class T>
    class Singleton
    {
    public:
        static T* GetInstance()
        {
            static Mutex mutex;
            if(!ms_instance)
            {
                Locker locker(mutex);
                if (!ms_instance)
                {
                    ms_instance = new T;
                }
            }

            return ms_instance;
        }

        static void SetInstance(T* pInst)
        {
            ms_instance = pInst;
        }

        static void DeleteInstance()
        {
            if (ms_instance)
            {
                delete ms_instance;
                ms_instance = NULL;
            }
        }
    private:
        class Garbo
        {
        public:
            ~Garbo()
            {
                if( Singleton::ms_instance )
                {

                    delete ms_instance;
                    ms_instance = NULL;
                }
            }
        };
        static Garbo garbo;
    protected:
        Singleton() {}
        ~Singleton() {}

        Singleton(const Singleton&) {}
        Singleton& operator=(const Singleton&) {}

    private:
        static T*	        ms_instance;

    };

    template<class T>
    T* Singleton<T>::ms_instance = 0;

　　

用法:

class Test : public Singleton<Test>

{

//your code

}

Test::GetInstance()->your method